A history of smoking is associated with improved survival in patients treated with mild therapeutic hypothermia following cardiac arrest

Abstract

Objectives To assess the association between smoking and survival with a good neurologic outcome in patients following cardiac arrest treated with mild therapeutic hypothermia (TH). Methods We conducted a retrospective observational study of a prospectively collected cohort of 188 consecutive patients following cardiac arrest treated with TH between May 2007 and January 2012. Smoking status was retrospectively collected via chart review and was classified as “ever” or “never”. Primary endpoint was survival to hospital discharge with a good neurologic outcome and was compared between smokers and nonsmokers. Logistic regression analysis was used to assess the association between smoking status and neurologic outcome at hospital discharge; adjusting for age, initial rhythm, time to return of spontaneous circulation (ROSC), bystander CPR, and time to initiation of TH. Results Smokers were significantly more likely to survive to hospital discharge with good neurologic outcome compared to nonsmokers (50% vs. 28%, p = 0.003). After adjusting for age, initial rhythm, time to ROSC, bystander CPR, and time to initiation of TH, a history of smoking was associated with increased odds of survival to hospital discharge with good neurologic outcome (OR 3.54, 95% CI 1.41–8.84, p = 0.007). Conclusions Smoking is associated with improved survival with good neurologic outcome in patients following cardiac arrest. We hypothesize that our findings reflect global ischemic conditioning caused by smoking.

Socioeconomic factors associated with outcome after cardiac arrest in patients under the age of 65

“…The association between smoking and favorable outcomes has been reported previously, and has been postulated to reflect preconditioning as a result of low level carbon monoxide exposure. 26 An alternative possibility is that smoking results in CAD making smokers more likely to have cardiac etiology arrest which is associated with better outcomes.…”

“Smoker’s Paradox” in Patients Treated for Severe Injuries: Lower Risk of Mortality After Trauma Observed in Current Smokers

“…15 Our findings are similar to studies investigating mortality outcomes in patients hospitalized for acute cardiac events, including cardiac arrest. [6][7][8] Although the etiology of the beneficial effect of smoking is unknown, it is possible that physiological changes associated with smoking or some component of tobacco smoke is protective during an ischemic event which can be brought on by injury, stroke, cardiac arrest, or heart attack. 7,22 For each of these conditions, with the exception of injury, current smokers were reported to have reduced in-hospital mortality by at least one study.…”

“…[6][7][8] Although the etiology of the beneficial effect of smoking is unknown, it is possible that physiological changes associated with smoking or some component of tobacco smoke is protective during an ischemic event which can be brought on by injury, stroke, cardiac arrest, or heart attack. 7,22 For each of these conditions, with the exception of injury, current smokers were reported to have reduced in-hospital mortality by at least one study. 1,5,6 This is the first report of the smoker's paradox in the injured patient population.…”

“…[1][2][3][4] Over the past 25 years, additional studies have found that smoking has protective effects against in-hospital mortality in patients who experience cardiac arrest, stroke, and heart failure. [5][6][7][8][9] The biologic mechanisms responsible for the smoker's paradox are underdetermined. However, laboratory studies have proposed that changes in endothelial function, enhanced thrombolysis, induced inflammation, faster epicardial flow, and remodeling of cardiac gap junctions are plausible explanations for the smoking paradox.…”

Functional, Cellular, and Molecular Remodeling of the Heart under Influence of Oxidative Cigarette Tobacco Smoke

“…Multiple preclinical studies confirmed the paradoxical effect of smoke on mortality after MI and attributed the beneficial effects to cardiac gap junction remodeling and preconditioning [ 27 , 112 ]. Smoking was independently associated with improved survival in patients with cardiac arrest and lower inpatient mortality in acute ischemic stroke and STEMI [ 107 , 110 , 111 ]. Results were attributed in part to changes in vascular reactivity due to a global smoking-induced ischemic conditioning.…”